Page:Popular Science Monthly Volume 44.djvu/638

622 ; where the reindeer occurs in the lower levels associated with the mammoth, woolly rhinoceros, hyena, etc., it is not abundant.

It seems more reasonable to suppose that these tropical forms were adapted to the cold climatal conditions in some way, as the mammoth and woolly rhinoceros were, or that the conditions were not as severe as the immense accumulations of ice would lead us to imagine, for, as we have seen, if the precipitation is great, the mean temperature need not necessarily be very low.

Prof. James Geikie thinks that during the Glacial epoch there were periods of high temperature, when the glaciers retreated and tropical animals migrated into the glacial region. However this may be, it is evident from what has been said that these tropical animals, with the woolly rhinoceros and mammoth, were either interglacial or preglacial or both. These data are important, as they fix the age of the associated human remains.

There is considerable diversity of opinion as to the value of the evidence of man's existence prior to the Pleistocene or early Quaternary—such evidence as we have being open to criticism or at least to the objection that it is not conclusive; it is founded principally upon roughly worked flints and flint chippings, perhaps and perhaps not made by man, as their occurrence can, at least to the satisfaction of some, be otherwise accounted for; also upon fossil bones of extinct mammals that bear markings supposed to have been made by contemporaneous man. Such bones have been found in both Pliocene and Miocene formations, and their incisions differently interpreted by different naturalists. Quite recently Prof. Cope has found in the Pliocene of southwestern Oregon obsidian implements of human manufacture associated and interbedded with remains of fossil birds, but by what agency they got there has not been determined.

The argument has been advanced as to Miocene man that, as all the mammalia of this period are extinct, it does not appear reasonable that man alone should survive the causes that proved so fatal to the rest of the mammalia. Against this it may be urged that man's superior intelligence would enable him to overcome adverse circumstances that would prove destructive to other forms. In fact, this superior intelligence may have been a potent factor in the destruction of the other forms.

In 1863 M. Desnoyes found in the gravel pit of Saint Prest, near Chartres, a leg bone (tibia) of a rhinoceros. It bore marks resembling those undoubtedly made by man on other more recent bones. Reasoning by analogy, the marks on the Saint Prest bone are also supposed to have been made by man. In the Victoria cave, Yorkshire, there was found a human leg bone (fibula). Both of these deposits have been considered by competent